Marine Interpretation Message
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
AGNT40 KWNM 111211
MIMATN

Marine Weather Discussion for N Atlantic Ocean
NWS Ocean Prediction Center Washington DC
711 AM EST SUN DEC 11 2016

.FORECAST DISCUSSION...Major features/winds/seas/significant
.weather for the North Atlantic Ocean W of 50W from 30N to 50N.

Update...06z ncep surface analysis shows a strong high pres ridge
moving e over the offshore waters, with a low pres trough
extending ne to sw across the eastern part of the mim area e of
the offshore zones. latest available ascat hi-res and ascat passes
from last night show 25 to 30 kt winds in nw flow over the nt1 and
ne nt2 waters...with mainly 15 to 20 kt winds across the remaining
offshore waters.

Main Weather Features...the ridge will pass e of the offshore
waters today and tonight. a warm front will lift ne over the nrn
nt2 and nt1 waters tonight and mon. a developing low will form
over the gulf of maine mon afternoon, then move off to the ne late
mon into early tue while pulling a strong cold front e and se
across the offshore waters. the cold front will stall and weaken
over the central and srn nt2 waters later tue and tue night.
another cold front will move se across the offshore waters wed and
wed night. a second developing low is expected to form along the
front near cape hatteras late wed, pass e over the nt2 area wed
night, then accelerate off to the ne thu. a series of troughs will
move se across the nt1 and nrn nt2 waters thu and thu night, as a
ridge builds off the carolina coast.

Models...the medium range models are in good overall agreement
across the offshore waters for today through tue, so the
representative gfs 10m solution will be used for the wind grids
through mon. a strong cold frontal passage is expected for later
mon through tue, so a blend of the gfs 10m/30m solutions will be
used to handle the stronger conditions associated with the front.
the ecmwf will be used for tue night through the rest of the
forecast period, since it has strong support from the ukmet. am
not planning to make any significant changes to the current
forecast trend.

Seas...the ecmwf wam has been initializing better than the wna
wavewatch over the offshore waters, so the ecmwf wam will be used
for the wave height grids for today before transitioning to a
50/50 blend of the ecmwf wam/wna wavewatch for tonight through
tue to smooth out some minor differences in the models. in order
to be consistent with the preferred ecmwf for tue night through
the rest of the forecast period, will go exclusively with the
ecmwf wam starting tue night.

Extratropical Storm Surge Guidance...N/A.

-----------------------------------------------------------------
PREVIOUS DISCUSSION...

Short Term...High pressure will slide east across the offshore
water today. A warm front will develop and lift northeast from
the mid-Atlantic states tonight. Low pressure will form along the
front over the Gulf of Maine Monday. Gales are still likely to
the south and southeast of the developing low pressure area
Monday, mainly from the central NT2 offshore waters northward.
The low will move east and pass just south of Nova Scotia Monday
night. As the low moves east, an associated cold front will move
southeast over NT1 and most of the NT2 waters Monday night. It
still appears as if the best chance for gales will be in advance
of the front, with the gales shifting east of the waters as the
cold front moves southeast over the region Monday night. Weak
high pressure will build over the most of region Tuesday behind
the front, with the front likely stalling over the far southern
NT2 waters. Overall, the 00Z models are in pretty good agreement
over the region through Tuesday. The 00Z GFS has remained pretty
consistent from its previous few cycles, and has good support
from non-GFS guidance as well. For the early morning package we
will use the 00Z GFS 10 meter winds for today into Monday, and
then use a tool which places the stronger first sigma layer winds
over the unstable areas and slightly lower 10 meter winds over
the stable areas Monday night into Tuesday as the cold front
crosses the region. This will result in only minor changes from
the previous few OPC forecasts for the early morning package.

Long Term...For Tuesday night through Thursday night the 00Z
models solutions begin to diverge. For the early morning package
we will trend the offshore forecast more toward the 00Z ECMWF
solution for this portion of the forecast. The 00Z ECMWF now has
good support from the 00Z UKMET during the middle portion of the
week. As a result, we expect low pressure to form along the
stationary front over the NT2 waters, near or east of Cape
Hatteras Tuesday night into early Wednesday, or about 12-24 hours
earlier than the previous forecast. At the same time another cold
front will move southeast over NT1 and northwest NT2 waters. The
low will track east of the NT2 waters by Wednesday night as strong
arctic high pressure builds from the plains toward the east coast.
Widespread gales are likely as the arctic air spills south and
southeastward over the waters Thursday and Thursday night.

Seas...For the early morning package it once again appears as if
the 00Z ECMWF wave model output is verifying a bit better than the
00Z Wavewatch III model output. As a result, we will stay close to
the ECMWF WAM guidance for today, use a 50-50 blend of the wave
watch and wam models for tonight through Tuesday, and then as we
trend the forecast winds toward the ECMWF model by Tuesday night
through Thursday night, also trend the wave height forecast toward
the 00Z ECMWF WAM for that time period.

.Extratropical Storm Surge Guidance...N/A.

.WARNINGS...Preliminary.

.NT1 New England Waters...
.ANZ800...Gulf of Maine...
     Gale Possible Thursday into Thursday night.
.ANZ805...Georges Bank west of 68W...
     Gale Monday.
     Gale Possible Thursday into Thursday night.
.ANZ900...Georges Bank east of 68W...
     Gale Monday.
     Gale Possible Thursday into Thursday night.
.ANZ810...South of New England...
     Gale Monday.
     Gale Possible Thursday into Thursday night.
.ANZ815...South of Long Island...
     Gale Monday.
     Gale Possible Thursday night.

.NT2 Mid-Atlantic Waters...
.ANZ820...Hudson Canyon to Baltimore Canyon...
     Gale Monday.
     Gale Possible Thursday night.
.ANZ915...Hudson Canyon to the Great South Channel...
     Gale Monday.
     Gale Possible Thursday into Thursday night.
.ANZ920...Baltimore Canyon to the Great South Channel...
     Gale Monday into Monday night.
     Gale Possible Thursday into Thursday night.
.ANZ905...The Great South Channel to the Hague Line...
     Gale Monday into Monday night.
     Gale Possible Thursday into Thursday night.
.ANZ910...East of the Great South Channel and south of 39N...
     Gale Monday into Monday night.
     Gale Possible Thursday into Thursday night.
.ANZ925...Outer Waters from Baltimore Canyon to Hatteras Canyon...
     Gale Monday into Monday night.
.ANZ930...Outer Waters from Hatteras Canyon to Cape Fear...
     Gale Monday into Monday night.

$$

.Forecaster Scovil/Mills. Ocean Prediction Center.


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.